[mpp] Migrate UnusedSourceSetsChecker to the new infra

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/NewMultiplatformIT.kt

@@ -1605,25 +1605,21 @@ open class NewMultiplatformIT : BaseGradleIT() {
 
         build {
             assertSuccessful()
-            assertContains(UnusedSourceSetsChecker.WARNING_PREFIX_ONE, UnusedSourceSetsChecker.WARNING_INTRO)
+            assertHasDiagnostic(KotlinToolingDiagnostics.UnusedSourceSetsWarning)
         }
 
         gradleBuildScript().appendText("\nkotlin { sourceSets { bar { dependsOn foo } } }")
 
         build {
             assertSuccessful()
-            assertContains(UnusedSourceSetsChecker.WARNING_PREFIX_MANY, UnusedSourceSetsChecker.WARNING_INTRO)
+            assertHasDiagnostic(KotlinToolingDiagnostics.UnusedSourceSetsWarning)
         }
 
         gradleBuildScript().appendText("\nkotlin { sourceSets { jvm6Main { dependsOn bar } } }")
 
         build {
             assertSuccessful()
-            assertNotContains(
-                UnusedSourceSetsChecker.WARNING_PREFIX_ONE,
-                UnusedSourceSetsChecker.WARNING_PREFIX_MANY,
-                UnusedSourceSetsChecker.WARNING_INTRO
-            )
+            assertNoDiagnostic(KotlinToolingDiagnostics.UnusedSourceSetsWarning)
         }
     }
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/android/KotlinAndroidMppIT.kt

@@ -6,7 +6,7 @@
 package org.jetbrains.kotlin.gradle.android
 
 import org.gradle.util.GradleVersion
-import org.jetbrains.kotlin.gradle.plugin.mpp.UnusedSourceSetsChecker
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinToolingDiagnostics
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.jetbrains.kotlin.gradle.testbase.TestVersions.AGP.AGP_70
 import org.jetbrains.kotlin.gradle.testbase.TestVersions.AGP.AGP_71
@@ -1015,10 +1015,8 @@ class KotlinAndroidMppIT : KGPBaseTest() {
             buildJdk = jdkVersion.location
         ) {
             build("assembleDebug") {
-                assertOutputDoesNotContain(UnusedSourceSetsChecker.WARNING_PREFIX_ONE)
-                assertOutputDoesNotContain(UnusedSourceSetsChecker.WARNING_PREFIX_MANY)
-                assertOutputDoesNotContain(UnusedSourceSetsChecker.WARNING_INTRO)
+                output.assertNoDiagnostic(KotlinToolingDiagnostics.UnusedSourceSetsWarning)
             }
         }
     }
-}
+}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/diagnostics/KotlinToolingDiagnostics.kt

@@ -54,4 +54,25 @@ object KotlinToolingDiagnostics {
             """.trimIndent()
         )
     }
+
+    object UnusedSourceSetsWarning : ToolingDiagnosticFactory(WARNING) {
+        operator fun invoke(sourceSetNames: Collection<String>): ToolingDiagnostic {
+
+            val cause = if (sourceSetNames.size == 1) {
+                "The Kotlin source set ${sourceSetNames.single()} was configured but not added to any Kotlin compilation.\n"
+            } else {
+                val sourceSetNames = sourceSetNames.joinToString("\n") { " * $it" }
+                "The following Kotlin source sets were configured but not added to any Kotlin compilation:\n" +
+                        sourceSetNames
+            }
+
+            val details =
+                """
+                |You can add a source set to a target's compilation by connecting it with the compilation's default source set using 'dependsOn'.
+                |See https://kotl.in/connecting-source-sets
+            """.trimMargin()
+
+            return build(cause + "\n" + details)
+        }
+    }
 }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/diagnostics/checkers/UnusedSourceSetsChecker.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.plugin.diagnostics.checkers
+
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinGradleProjectChecker
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinGradleProjectCheckerContext
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinToolingDiagnostics
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinToolingDiagnosticsCollector
+import org.jetbrains.kotlin.gradle.plugin.sources.android.androidSourceSetInfoOrNull
+import org.jetbrains.kotlin.gradle.plugin.sources.internal
+
+internal object UnusedSourceSetsChecker : KotlinGradleProjectChecker {
+
+    override fun KotlinGradleProjectCheckerContext.runChecks(collector: KotlinToolingDiagnosticsCollector) {
+        val unusedSourceSets = multiplatformExtension?.sourceSets.orEmpty()
+            // Ignoring Android source sets
+            .filter { it.androidSourceSetInfoOrNull == null }
+            .filter { it.internal.compilations.isEmpty() }
+
+        if (unusedSourceSets.isNotEmpty()) {
+            collector.report(project, KotlinToolingDiagnostics.UnusedSourceSetsWarning(unusedSourceSets.toSet().map { it.name }))
+        }
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinMultiplatformPlugin.kt

@@ -191,8 +191,6 @@ class KotlinMultiplatformPlugin : Plugin<Project> {
             KotlinBuildStatsService.getInstance()?.report(StringMetrics.MPP_PLATFORMS, targetName)
         }
 
-        UnusedSourceSetsChecker.checkSourceSets(project)
-
         project.launchInStage(KotlinPluginLifecycle.Stage.ReadyForExecution) {
             project.runProjectConfigurationHealthCheck {
                 checkSourceSetVisibilityRequirements(project)

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/UnusedSourceSetsChecker.kt

@@ -1,52 +0,0 @@
-/*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.gradle.plugin.mpp
-
-import org.gradle.api.Project
-import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
-import org.jetbrains.kotlin.gradle.plugin.*
-import org.jetbrains.kotlin.gradle.plugin.KotlinPluginLifecycle
-import org.jetbrains.kotlin.gradle.plugin.launchInStage
-import org.jetbrains.kotlin.gradle.plugin.sources.android.androidSourceSetInfoOrNull
-import org.jetbrains.kotlin.gradle.plugin.sources.internal
-
-object UnusedSourceSetsChecker {
-    const val WARNING_PREFIX_ONE =
-        "The Kotlin source set"
-
-    const val WARNING_PREFIX_MANY =
-        "The following Kotlin source sets were"
-
-    const val WARNING_INTRO = "configured but not added to any Kotlin compilation"
-
-    const val WARNING_BOTTOM_LINE =
-        "You can add a source set to a target's compilation by connecting it with the compilation's default source set using 'dependsOn'.\n" +
-                "See https://kotl.in/connecting-source-sets"
-
-    private fun reportUnusedSourceSets(project: Project, sourceSets: Set<KotlinSourceSet>) {
-        require(sourceSets.isNotEmpty())
-        val message = when (sourceSets.size) {
-            1 -> "$WARNING_PREFIX_ONE ${sourceSets.single().name} was $WARNING_INTRO. $WARNING_BOTTOM_LINE"
-            else -> {
-                val list = sourceSets.joinToString("\n", "\n", "\n") { " * ${it.name}" }
-                "$WARNING_PREFIX_MANY $WARNING_INTRO:$list$WARNING_BOTTOM_LINE"
-            }
-        }
-        project.logger.warn("\n" + message) // make sure the message stands out
-    }
-
-    fun checkSourceSets(project: Project) {
-        project.launchInStage(KotlinPluginLifecycle.Stage.ReadyForExecution) {
-            val unusedSourceSets = project.kotlinExtension.sourceSets
-                // Ignoring Android source sets
-                .filter { it.androidSourceSetInfoOrNull == null }
-                .filter { it.internal.compilations.isEmpty() }
-            if (unusedSourceSets.isNotEmpty()) {
-                reportUnusedSourceSets(project, unusedSourceSets.toSet())
-            }
-        }
-    }
-}